To provide wireless connectivity between a computing device (e.g., portable laptop computer) and other computing devices (laptops, servers, etc.), peripherals (e.g., printers, mouse, keyboard, etc.) or communication devices (modem, smart phones, etc.), it is necessary to equip such devices with antennas. For example, with portable laptop computers, an antenna may be located either external to the device or integrated (embedded) within the device (e.g., embedded in the display unit).
For example, FIG. 1 is a diagram illustrating various conventional embodiments for providing external antennas for a laptop computer. A monopole antenna (10) can be located at the top of a display unit of the laptop computer. Alternatively, an antenna (11) can be located on a PC card (12). The laptop computer will provide optimum wireless connection performance with the antenna (10) mounted on the top of the display due to the very good RF (radio frequency) clearance. There are disadvantages associated with laptop designs having external antennas, however, such as high manufacture costs, possible reduction of the strength of the antenna (e.g., for the PC card antenna 12), susceptibility to damage, and the effects on the appearance of the laptop due to the antenna.
Other conventional laptop antenna designs include embedded designs wherein one or more antennas are integrally built (embedded antenna) within a laptop. For example, FIG. 2 illustrates conventional embedded antenna implementations, wherein one or more antennas (20, 21, 22) (e.g., whip-like or slot embedded antennas) are embedded in a laptop display. In one conventional embodiment, two embedded antennas (20, 21) are placed on the left and right edges of the display. The use of two antennas (as opposed to one antenna) will reduce the blockage caused by the display in some directions and provide space diversity to the wireless communication system. In another conventional configuration, one antenna (20 or 21) is disposed on one side of the display and a second antenna (22) is disposed in an upper portion of the display. This conventional antenna configuration may also provide antenna polarization diversity depending on the antenna design used.
Although embedded antenna designs can overcome some of the above-mentioned disadvantages associated with external antenna designs (e.g., less susceptible to damage), embedded antenna designs typically do not perform as well as external antennas. One conventional method to improve the performance of an embedded antenna is to dispose the antenna at a certain distance from any metal component of a laptop. For example, depending on the laptop design and the antenna type used, the distance between the antenna and any metal component should be at least 10 mm. Another disadvantage associated with embedded antenna designs is that the size of the laptop must be increased to accommodate antenna placement, especially when two or more antennas are used (as shown in FIG. 2).
Continuing advances in wireless communications technology has lead to significant interest in development and implementation of wireless computer applications. For example, the 2.4 GHz ISM band is widely used in wireless network connectivity. In particular, many laptop computers will incorporate the known Bluetooth technology as a cable replacement between portable and/or fixed electronic devices and IEEE 802.11b technology for WLAN (wireless local area network). If an 802.11b device is used, the 2.4 GHz band can provide a data rate up to 11 Mbps. To provide even higher data rates and provide compatibility with worldwide wireless communication applications and environments, 802.11a wireless devices that operate in the 5 GHz band in the 5.15–5.85 GHz frequency range can provide data rates up to 54 Mbps. Further, 802.11g devices operating in the 2.4 GHz band can also reach a data rate of 54 Mbps. However, 802.11a devices with proposed channel binding techniques will extend the data rate to 108 Mbps. Moreover, newer WLAN devices have been developed which combine a/b/g. Accordingly, the demand for multiband antennas that are designed for efficient operation in multiple frequency bands (e.g., the 2.4 and 5 GHz bands) is increasing.